Recording apparatus with two charging units for achieving uniform after-transfer zones distribution

Abstract

A recording apparatus has a development unit for depositing a toner on an electrostatic latent image on the outer surface of a photosensitive drum while attractively collecting a residual toner on the surface of the photosensitive drum, a transfer charger device for transferring the toner image to a transfer sheet, a conductive brush for uniformalizing a residual toner distribution on the photosensitive drum, after a transfer step has been carried out, and at the same time charging the surface of the photosensitive drum, and a scorotron charger located on the downstream side of the conductive brush, but on the upstream side of the exposure device, and assisting the charging of the drum surface by the conductive brush. The surface of the drum charged by the scorotron charger is exposed by a light beam to provide an electrostatic latent image thereon.

What is claimed is: 
     
       1. A recording apparatus for performing an image recording based on an electrophotographic system, comprising: electrostatic latent image carrier means having a photosensitive surface and being rotatable in one direction;   exposure means for producing a partial decline in a charged area on the surface of the electrostatic latent image carrier means to provide an electrostatic latent image on the electrostatic latent image carrier means;   developing means for depositing a toner on the electrostatic latent image provided by the exposure means to form a toner image, while attractively collecting a toner remaining, as a residual toner, on the surface of the electrostatic latent image carrier means after a transfer step;   image recording means for having the toner image recorded thereon;   transfer means for transferring the toner image which has been formed by the developing means to the image recording means for recording the toner image on the image recording means;   residual the toner image uniformalizing/charging means for uniformalizing a residual toner distribution on the surface of the electrostatic latent image carrier means which is left after the transferring of toner by the transfer means, while charging the surface of the electrostatic latent image carrier means; and   auxiliary charging means, including a corona charger, located on a downstream side of the residual toner image uniformalizing/charging means, but on an upstream side of the exposure means, with the rotational direction of the electrostatic latent image carrier means as a reference, and operable in conjunction with said residual toner image uniformalizing/charging means for assisting in charging of the surface of the electrostatic latent image carrier means by the residual toner image uniformalizing/charging means, said auxiliary charging means producing a discharge current;   wherein a relation |Ia|<|Ico| is satisfied, where   Ia: a discharge current in the auxiliary charging means when a charger potential on the surface of the electrostatic latent image carrier means necessary for toner image formation is given by V0; and   Ico: a discharge current in the auxiliary charging means when the surface of the electrostatic latent image carrier means is charged to a potential V0 by the auxiliary charging means alone.   
     
     
       2. The recording apparatus according to claim 1, wherein a relation |Va|<|V0| is satisfied, where V0: a charge potential on the surface of the electrostatic latent image carrier means necessary for toner image formation in which case a discharge current in the auxiliary charging means is given by said Ia; and   Va: a charge potential on the surface of the electrostatic latent image carrier means, provided that, when the surface of the electrostatic latent image carrier means is charged by the auxiliary charging means alone, the discharge current in the auxiliary charging means is restricted to said Ia.   
     
     
       3. The recording apparatus according to claim 1, wherein: the corona charger comprises a scorotron charger;   a relation |Ia|<|Ico| is satisfied, where V0: a charge potential on the surface of the electrostatic latent image carrier means necessary for toner image formation, when the corona charger of the auxiliary charging means comprises a scorotron charger;     a relation |Vo|<|Vg| is satisfied, where Vg: a voltage applied to the grid of the scorotron charger when used in combination with the residual toner image uniformalizing/charging means.